Telogen effluvium is a condition that causes temporary, diffuse hair loss throughout all areas of the scalp. According to Harvard Health Publications, it can be triggered by extreme psychological stress, major physical trauma, surgery, high fever, severe infections, dramatic weight loss, extreme changes in diet, iron deficiency and certain prescription medications. Thyroid diseases that result in hypothyroidism or hyperthyroidism can also cause telogen effluvium, as can hormonal changes brought on by childbirth or menopause. Once the underlying cause is treated, telogen effluvium typically resolves itself within six months, but some cases can persist for longer. While the average person loses approximately 100 hairs per day, patients with telogen effluvium are known to lose as many as 300 hairs per day.